1. Field of the Invention
The present invention relates to a system for trapping flying insects such as mosquitoes, no-see-ums, and other insects
2. Description of Related Art
Each year mosquito-transmitted diseases are responsible for over 3 million deaths and 300 million clinical cases. It is estimated that the worldwide costs associated with the treatment of such mosquito-transmitted diseases runs well into the billions of dollars. In many regions mosquitoes are the primary transmitters of debilitating diseases such as malaria, yellow fever, dengue fever, encephalitis, West Nile virus, sleeping sickness, filariasis, typhus and plague. In addition to the illnesses and deaths caused to humans, mosquito-transmitted diseases are a major cause of economic losses to livestock industries due to veterinary diseases. Further, mosquito-transmitted diseases pose an ever-present concern to regions dependent on revenues from tourism. Specifically, the presence of such diseases in a given region is believed to impact the willingness of tourists to select that region as a tourism destination.
With increased travel and world commerce it also is expected that some of these diseases will become major health problems in the continental United States and elsewhere. For example, the emergence of the West Nile virus in temperate regions of Europe and North America supports this expectation, which represents a threat to the health of the general public, as well as to the health of horses and other animals. The West Nile virus can result in encephalitis (inflammation of the brain) in humans and horses, and mortality in domestic animals and wild birds.
A number of methods for controlling mosquito populations or repelling mosquitoes have been proposed in the past. Examples of these are discussed herein below. As will be appreciated from the following discussion, each of these methods have significant drawbacks which render them impractical or ineffective.
One well-known method for suppressing mosquito populations is the use of chemical pesticides, such as DDT and Malathion. There are basically two types of mosquito pesticides available—adulticides and larvicides. Adulticides are chemicals used to kill mosquitoes that have developed to the adult stage. Infested areas are sprayed primarily from aircraft or motor vehicles. Efficacy of the sprayed chemicals is typically dependent upon wind, temperature, humidity, and time of day, the particular mosquito's resistance to the chemical used, and the base efficacy of the particular chemical. Adulticides must be applied for each generation of adults produced by rain, tidal flooding, or other periodic egg hatching trigger, and have a typical efficacy window of only ½ day. As such, these chemicals must be applied at a time when maximum contact with adult mosquitoes can be expected.
Larvicides, on the other hand, are applied to water sources to kill the larvae before they become adult mosquitoes. Larvicides generally take the form of one of three varieties: (1) an oil applied to the water surface that prevents the larvae from breathing and thus drowns them, (2) a bacteria, such as BTI (bacillus thuringiensis israelensis), which attacks the larvae and kills them, or (3) a chemical insect growth regulator (e.g., methoprene) that prevents the larvae from developing to the adult stage. However, larvicides often are not particularly effective for a variety of reasons. For example, most larvicides have a short efficacy period and must be applied to the water while the immature mosquitoes are at a particular stage of growth. Also, several species of mosquitoes, such as tree-hole breeders, root-swamp breeders, and cattail-marsh breeders, are not easily controlled with larvicides since the larvae either do not come to the surface (e.g., cattail marsh mosquito) or the water sources are so difficult to locate that the larvicide's cannot be economically applied (e.g., tree holes). Additionally, the mosquito that carries the West Nile virus (Culex Pippiens) lives and breeds around humans in gutters, underground drains, flower pots, birdbaths, etc. This not only makes the spraying of insecticides impractical due to the difficulty associated with effectively targeting such areas, many people are also uncomfortable with the use of chemical pesticides so close to their homes.
Regardless of their alleged efficacy, or lack thereof, the use of chemical pesticides has been reduced dramatically in both the United States and worldwide. A primary reason for this reduction is attributable to the rising public awareness of the potential health hazards related to pesticide use. Specifically, general public perception of the long-term health hazards presented by certain chemicals, such as DDT, has led to the banning of their use for mosquito control in many parts of the United States and other countries. Additionally, increasing pesticide resistance among mosquitoes has reduced the effectiveness of the chemicals conventionally used, thus bolstering the argument that the supposed benefits of chemical pesticides do not outweigh public health risks.
To some extent, natural predators also control mosquito populations. For example, certain fish and dragonflies (as both nymphs and adults) are reported to eat mosquito larvae and adults. Additionally, it is known that certain bats and birds also prey on mosquitoes. Some people, particularly those opposed to the use of chemical pesticides, have advocated that natural predators should be relied on as an environmentally safe means for controlling mosquito populations. Unfortunately, efforts in the past to utilize natural predators for effectively controlling mosquito populations have proven ineffective. For example, large bat towers were erected in three cities in the South during the 1920's with high expectations that the bats living in these towers would control mosquito populations. However, these towers were ineffective at adequately controlling the local mosquito populations. Studies of the stomach contents of the bats found that mosquitoes made up less than 1% of their food source.
Many people rely on repellents to keep mosquitoes away from their person, or from a certain area. These repellents by their nature do nothing to actually control the mosquito population; instead, they simply offer temporary relief to the person employing the repellent. Repellents can be either topical or aerial, and can take many forms, including lotions, sprays, oils (e.g., “Skin-So-Soft”), coils, and candles (e.g. citronella), among others. The most common repellents (lotions, sprays, and oils) are those that are used on the clothing or body. Many of these repellents do not actually “repel” mosquitoes per se—instead, some repellents simply mask the factors (carbon dioxide, moisture, warmth and lactic acid), which attract a mosquito to its host. Although these repellents are fairly inexpensive, they often have an offensive odor, are greasy, and are effective for only a limited duration. It has also been found that repellents, which contain DEET, or ethyl hexanediol, actually become attractive to mosquitoes after a period of time. Therefore, it is advisable when using repellents to wash them off or reapply fresh repellent when the protective period has passed.
In addition to being unpleasant, many repellents are coming under close scrutiny with respect to the potential long-term health hazards they may pose. DEET, considered by many entomologists to be the best repellent available, has been marketed for over 30 years, and is the primary ingredient of many well-known commercial sprays and lotions. Despite the long-term widespread use of DEET, the U.S. Environmental Protection Agency (EPA) believes that DEET may have the ability to cause cancers, birth defects, and reproductive problems. In fact, the EPA issued a consumer bulletin in August 1990 in which they stated that a small segment of the population may be sensitive to DEET. Repeated applications—particularly on small children—may sometimes cause headaches, mood changes, confusion, nausea, muscle spasms, convulsions or unconsciousness.
Mosquito coils have been sold for many years as a means for repelling mosquitoes. These coils are burnt to emit a repellent smoke. Products manufactured some 20 years ago were sold under the trade name Raid Mosquito Coils and contained the chemical Allethrin. Recent products are trade named OFF Yard & Patio Bug Barriers and contain the chemical Esbiothrin. These products may provide some relief from mosquito activity; however, they do not reduce the number of mosquitoes in a region, and they emit smoke and chemicals into the vicinity. Also, with even the slightest breeze, their potential effect is diminished, as the smoke and chemicals are dispersed over a large area and thus become diluted and less effective.
Many people have also touted the benefits of citronella in repelling mosquitoes, whether it is in the form of candles, plants, incense, or other mechanisms. According to a recent study, citronella-based products have been shown to be only mildly effective in repelling mosquitoes and then only when the candles were placed every three feet around a protected area. This treatment was only slightly more effective than burning plain candles around a protected area. In fact, it is believed that burning the candles increases the amount of carbon dioxide in the air, causing more mosquitoes to be drawn into the general area rather than reducing the number of mosquitoes in the area. Despite these drawbacks, the current market for citronella-based products is quite large.
Introduced in the late 1970s, the familiar “black-light” electrocution devices, referred to as “bug zappers,” were initially a commercial success. Although essentially ineffective at killing mosquitoes, bug zappers sell at a current rate of over 2,000,000 units annually. The ineffectiveness of these devices at killing mosquitoes has been proven in academic studies and the personal experiences of many bug zapper owners. Specifically, electrocution devices are ineffective at killing mosquitoes because they do not attract most mosquitoes. The reason for this is that these devices only attract insects that are attracted to light, which is not the case with most species of mosquitoes.
U.S. Pat. No. 6,145,243 (“the '243 patent”) discloses an insect trapping device developed by the assignee of the present application, American Biophysics Corporation of East Greenwich, R.I. The device of the '243 patent discloses the basic construction of a device that uses combustion to generate a flow of carbon dioxide for attracting mosquitoes and other flying insects towards an inlet on the device. A vacuum draws the insects attracted by the carbon dioxide through the inlet and into a trap chamber. The trap chamber includes a disposable mesh bag in which the mosquitoes become dehydrated. When the bag becomes full, it can be removed and replaced. U.S. patent application Ser. No. 2003/0084604A1 (“the '604 application”), also owned by American Biophysics, discloses another device for attracting and capturing insects that also uses combustion to generate carbon dioxide.
While the device disclosed in the '243 patent and the '604 application have been commercially successful for American Biophysics Corporation, it would be desirable to provide a system that is of significantly lower cost, and thus available to more consumers. It is believed that the additive impact of widespread use of this technology will help lead to better control of mosquito and other flying insect populations and, in turn, to reduced incidents of insect transmitted diseases.